Bar joists



Nov. 19, 1963 R. E. BRADDON BAR JOISTS Filed June 6, 1960 IN VEN TOR. RALPH. E. BRADDON BY FOR ,fl 7M? AT e/vEYs United States Patent 3,111,207 BAR JOISTS Ralph E. Braddon, 1436 E. 86th St., Cleveland 6, Ohio Filed June 6, 1960, Ser. No. 34,099 3 Claims. (Cl. 189-37) This invention relates to triangular joists, and more particularly to hollow chord construction of triangular joists.

The trend in modern construction is toward highstrength, lightweight joists, permitting greater spans, It is desirable in constructing joists for building support that maximum strength be obtained from a minimum weight. This invention pertains to a joist construction which is simplified and supports a greater weight per unit than prior joists of comparable size.

There have been many proposals for open-web joist construction. There have also been prior proposals for joists which are triangular in cross section having open-web construction; e.g., U.S. Patent No. 2,241,617. There are many advantages to the use of triangular steel joists. Included among these advantages are inherent stability and strength not found in other open-web construction.

Triangular joist construction and use have not met with wide acceptance for the reason that the prior attempts have been limited to constructions virtually identical to a single joist. The main difference has been simply the use of a common bottom web with some top bracing to hold the joist in triangular relationship. With this invention, a joist having many advantages over either the prior single or triangular joist construction is obtained through innovations made possible by the use of a new system of construction of the chord and bracing. There are additional benefits available in the form of hollow condui-ts for carrying electrical wiring and other appurtenances needed in building.

One of the principal objects of this invention is to provide a new and novel chord construction for a joist, in a form which provides access for better resistance welding during assembly and which can be closed to a form presenting a minimum of exposed surface for weathering action and painting; is self-draining and self-cleaning; and also provides enclosed conduit space for building service lines.

Another object of this invention is to provide a configuration which provides means for attachment of crossbracing which is neat and simple and has exceptionally good structural characteristics combined with pleasing lines for better aesthetic qualities.

Another of the principal objects of this invention is to provide a joist, triangular in cross section, having hollow,

chord members so constructed as to drain 01f moisture and be largely self-cleaning.

A more particular object of this invention is to provide a joist structure, triangular in cross section, having hollow members which can be left open during assembly to facilitate resistance welding of bracing members and which can be closed thereafter to prevent the accumulation of moisture inside the member.

A detailed object of this invention is to provide hollow chord members of such a design that bracing members can be attached and the chords subsequently closed from the atmosphere, either during the manufacture or after, or even when the joist is in place in the structure.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view of a metal joist of triangular cross section;

3,111,207 Patented Nov. 19., 1963 FIGURE 2 is a sectional view of the unit as a whole taken along the line 22 of FIGURE 1;

FIGURE 3 is a sectional view of the lower chord member, showing its closed position in phantom;

FIGURE 4 is a sectional view of a lower chord member, showing an alternate method of closing the chord;

FIGURE 5 is a sectional view of an upper chord member, showing the closed position in phantom; and

FIGURE 6 is a sectional view of an upper chord member, showing an alternate method of closing the member.

Referring now to FIGURE 1, a steel bar joist, triangular in cross section, is designated generally by the numeral 10. The joist includes an elongated lower chord member 11, and a pair of elongated and laterally spaced upper chord members 12. Each upper chord member 12 has an internal cavity 34 defined by an upper wall 14, a side wall 15, and a lower wall 16, jointly indicated by reference number 13. The upper wall 14 has an extension section 22 which projects beyond the side wall 15 when in the assembled position. Thus, projection 22 forms a convenient means of attachment of the transverse web pieces.

Braces 20 are provided which are welded to the extensions 22 and the side portions 15 of the upper chord members :12, thus interconnecting the two upper chord members 12 in a trussed relationship. Braces 21 are provided, each of which is welded between a lower surface 16 of an upper chord member 12 and an upper surface 18 of the lower chord member 11. Thus, a strong rigid triangular joist is formed.

The lower chord member 11 has a wall 17 defining an internal cavity 19. The wall 17 includes a pair of upper surfaces 18, each of which is sloped off a horizontal position to promote drainage of any moisture collected there- The lower chord member 11 is constructed so that in the assembly an opening 24- communicating with the internal cavity is facing downward. This opening may be closed by pressing the sides together as shown in phantom in FIGURE 3 or by the provision of a closure strip 25 snapped in place with a spring clip extension 26 shown in FIGURE 4, or by fixtures inserted into the opening in place of or in addition to the strips 25.

Referring now to FIGURES 5 and 6, two different methods of constructing the upper chords of a triangular joist are shown. In each case the upper chord member =12 is formed so that there is an opening 23 to permit access to the internal cavity 34. Braces 21 are welded between the lower Wall 16 of the selectedupper chord member and respective upper surfaces 18 of the lower chord member 11. After the bracing members 21 have been welded in place the opening 23 is closed by bending. in the preferred embodiment this closing is sealed by welding.

FIGURE 5 indicates one method by which each upper chord member can be formed and later closed. In this procedure the side wall 15 is bent outwardly to provide the opening 23. After the braces 21 are welded between the lower surface of wall 16 of the upper chord member 12 and the upper surface 18 of the lower chord member 11, the side wall 15 of the upper chord member is bent upwardly and inwardly to contact the lower surface of upper wall 14, thus closing the opening 23.

FIGURE 6 indicates an alternate method of forming the upper chord member. In this embodiment the upper wall 14 with extension 22 is formed bent upward to provide the opening 23 for the welding operation to attach the bracing 21 as in the above procedure. After the bracing 21 is welded to the lower wall 16 of each upper chord and the upper surface 18 of the bottom chord 1 1, the opening 23 is closed by bending the wall 14 to 3 close against the edge of wall 15. When the openings 23 of the upper chords are closed, the bracing pieces 20 can be placed and welded between the upper chords.

FIGURE 3 indicates a form of lower chord which permits closure after welding of the inter-chord bracing by bending of the sides of the chord together.

FIGURE 4 indicates a form of lower chord which permits closure after welding of the inter-chord bracing by attachment of a cover strip held in place by separate means such as clips.

Although the invention has been described generally and has shown two specific embodiments of upper and lower chord construction, it is believed-that the invention consists broadly in the novel concept of overall construction resulting in a greatly improved practical construction and practical means of forming this construction suitable for acceptance by modern architects and builders.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred forms has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A joist of triangular cross-section, comprising, a lower chord having a top surface composed of first and second substantially flat portions meeting at a ridge and side walls extending downwardly vfrom the top surface, said chord being hollow with said walls spaced from and extending about a central axis located in the hollow interior of the chord, said chord having a closable bottom opening for access into said hollow interior, first and second top chords having a hollow configurationdefined by walls extending about a longitudinal axis, said walls of the first chord including a fiat bottom wall, first and second side walls, and a top wall, said top wall extending beyond said first side wall, said first and second top chords having reverse image cross-section configurations with the first walls facing and with the extensions being toward one another, said bottom walls of said first top chord being substantially parallel to said first flat portion of the bottom chord, said bottom Wall of said second top chord being substantially parallel to said second flat portion of the bottom chord, structural members welded at each end interconnecting said parallel faces and forming a V structure, and cross bracing members welded between said first walls of said top chord members with said top extension walls of each top chord member overlying and Welded to the cross brace member.

2. In the joist as defined in claim 1, said chords all being fabricated of sheet material.

3. A joist construction of triangular cross-section comprising:

(a) a pair of hollow chords extending in a common plane,

(b) a plurality of longitudinally spaced cross-braces extending between opposed side walls of said pair of chords,

(0) each of said pair of chords including a flange ex- References Cited in the file of this patent UNITED STATES PATENTS 431,203 Dithridge July 1, 1890 1,951,810 Schatfert Mar. 20, 1934 2,097,722 Coddington Nov. 2, 1937 2,241,617 Rubin May 13, 1941 FOREIGN PATENTS 614,171 Great Britain Dec. 10, 1948 185,549 Austria May 11, 1956 70,643 France Dec. 29, 1958 (Addition to No. 1,137,631) 592,984 Canada Feb. 23, 1960 

1. A JOIST OF TRIANGULAR CROSS-SECTION, COMPRISING, A LOWER CHORD HAVING A TOP SURFACE COMPOSED OF FIRST AND SECOND SUBSTANTIALLY FLAT PORTIONS MEETING AT A RIDGE AND SIDE WALLS EXTENDING DOWNWARDLY FROM THE TOP SURFACE, SAID CHORD BEING HOLLOW WITH SAID WALLS SPACED FROM AND EXTENDING ABOUT A CENTRAL AXIS LOCATED IN THE HOLLOW INTERIOR OF THE CHORD, SAID CHORD HAVING A CLOSABLE BOTTOM OPENING FOR ACCESS INTO SAID HOLLOW INTERIOR, FIRST AND SECOND TOP CHORDS HAVING A HOLLOW CONFIGURATION DEFINED BY WALLS EXTENDING ABOUT A LONGITUDINAL AXIS, SAID WALLS OF THE FIRST CHORD INCLUDING A FLAT BOTTOM WALL, FIRST AND SECOND SIDE WALLS, AND A TOP WALL, SAID TOP WALL EXTENDING BEYOND SAID FIRST SIDE WALL, SAID FIRST AND SECOND TOP CHORDS HAVING REVERSE IMAGE CROSS-SECTION CONFIGURATIONS WITH THE FIRST WALLS FACING AND WITH THE EXTENSIONS BEING TOWARD ONE ANOTHER, SAID BOTTOM WALLS OF SAID FIRST TOP CHORD BEING SUBSTANTIALLY PARALLEL TO SAID FIRST FLAT PORTION OF THE BOTTOM CHORD, SAID BOTTOM WALL OF SAID SECOND TOP CHORD BEING SUBSTANTIALLY PARALLEL TO SAID SECOND FLAT PORTION OF THE BOTTOM CHORD, STRUCTURAL MEMBERS WELDED AT EACH END INTERCONNECTING SAID PARALLEL FACES AND FORMING A "V" STRUCTURE, AND CROSS BRACING MEMBERS WELDED BETWEEN SAID FIRST WALLS OF SAID TOP CHORD MEMBERS WITH SAID TOP EXTENSION WALLS OF EACH TOP CHORD MEMBER OVERLYING AND WELDED TO THE CROSS BRACE MEMBER. 